The Swedish term "mogen, mogna, fyllig" matches the English term "mellow"

other swedish words that include "mogna" : english :
mognad maturity
mogna ripen
mognar ripens
other swedish words that include "fyllig" : english :
fyllig, fryntlig buxom
fyllig full-flavoured
knubbig, fyllig, dimpa ner, knubbig, fyllig plump